Aldehyde dehydrogenase from the bioluminescent bacterium, Vibrio harveyi , catalyses the oxidation of long-chain aliphatic aldehydes to acids. The enzyme is unique compared with other forms of aldehyde dehydrogenase in that it exhibits a very high specificity and affinity for the cofactor NADP + . Structural studies of this enzyme and comparisons with other forms of aldehyde dehydrogenase provide the basis for understanding the molecular features that dictate these unique properties and will enhance our understanding of the mechanism of catalysis for this class of enzyme. The X-ray structure of aldehyde dehydrogenase from V. harveyi has been solved to 2.5-A resolution as a partial complex with the cofactor NADP + and to 2.1-A resolution as a fully bound ‘holo’complex. The cofactor preference exhibited by different forms of the enzyme is predominantly determined by the electrostatic environment surrounding the 2´-hydroxy or the 2´-phosphate groups of the adenosine ribose moiety of NAD + or NADP + , respectively. In the NADP + -dependent structures the presence of a threonine and a lysine contribute to the cofactor specificity. In the V. harveyi enzyme an arginine residue (Arg-210) contributes to the high cofactor affinity through a pi stacking interaction with the adenine ring system of the cofactor. Further differences between the V. harveyi enzyme and other aldehyde dehydrogenases are seen in the active site, in particular a histidine residue which is structurally conserved with phosphorylating glyceraldehyde-3-phosphate dehydrogenase. This may suggest an alternative mechanism for activation of the reactive cysteine residue for nucleophilic attack.

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Crystal structure of the NADP+-dependent aldehyde dehydrogenase from Vibrio harveyi: structural implications for cofactor specificity and affinity

http://www.chem.ualberta.ca/~campbell/resources/PDFs/1.pdf

Properties and Kinetic Analysis of UDP-glucose Dehydrogenase from Group A Streptococci IRREVERSIBLE INHIBITION BY UDP-CHLOROACETOL

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2897%2900228-7

Molecular characterization of PadA, a phenylacetaldehyde dehydrogenase from Escherichia coli

A Novel α-Ketoglutaric Semialdehyde Dehydrogenase EVOLUTIONARY INSIGHT INTO AN ALTERNATIVE PATHWAY OF BACTERIAL l-ARABINOSE METABOLISM

Studies on the mechanism of ring-hydrolysis in phenylacetate degradation - A metabolic branching point

Fatty aldehyde dehydrogenase (Vh.ALDH) from the luminescent bacterium, Vibrio harveyi, may be implicated in controlling luminescence as it catalyzes the oxidation of the fatty aldehyde substrate for the light-emitting reaction. On the basis of the amino-terminal sequence of Vh.ALDH, a degenerate probe was used to screen a genomic library of V harveyi in pBR322, a positive clone was selected containing the Vh.ALDH gene and expressed in Escherichia coli, and the enzyme was purified to homogeneity. Although the sequence of the V. harveyi ALDH significantly diverged from other aldehyde dehydrogenases, mutation of a conserved cysteine implicated in catalysis completely inactivated the enzyme without loss of its ability to bind nucleotides, consistent with a catalytic role for this residue. Using absorption and fluorescence assays for NAD(P)H, it was shown that NAD+ and NADP+ bound to the same site and that saturation of Vh.ALDH with NADP+ occurred with a Michaelis constant (Km = 1.4 microM) over 40 times lower than that reported for other aldehyde dehydrogenases. Although V. harveyi aldehyde dehydrogenase is unique in terms of its high specificity for NADP+, the identification of a catalytic conserved cysteine in Vh.ALDH clearly indicates that a highly related mechanism and structure have been retained among even the most diverged aldehyde dehydrogenases.

M Vedadi

Papers

Involvement of cysteine 289 in the catalytic activity of an NADP+-specific fatty aldehyde dehydrogenase from Vibrio harveyi